I'm saying this because it is real. Just imagine, Ethereum has built many tokens inside the blockchain and many people launched ICOs which most of them are totally weird and fake, but some of them are not. People usually like to trade their ethereum and turn it into a token where it can be determined as a "future asset" and it cannot be sold until they had listed on an exchange. The companies who launched the ICOs are usually selling the ethereum which gotten from their ICO in droves, in which it can make a dump on the Ethereum market.
Unfortunately none on your thesis is based on any facts. Most ICO's did not sell the Ethereum they raised, they stupidly hung on to it even though most of their future expenses would be paid in fiat currency. The bear market began in January when ICO's were still raising huge amounts of money. This bear market was caused by the hype of 2017 that drove prices up to unsustainable levels.